Translation guide
Expresses that something is resistant to water, does not let water in, or is suitable for use in wet conditions. Japanese uses different words depending on whether you mean a material, a watch, clothing, or making something waterproof.
Describing an item or material that resists water penetration, often used for watches, electronics, and outdoor gear.
The most common and general term for 'waterproof' or 'water-resistant'. Used as a noun or adjective (often with の). Appears on product labels.
This watch is waterproof.
a waterproof jacket
Literally 'water-resistant'. Often used in technical contexts or for materials that withstand water to some degree, but may not be fully submersible.
Specifically for garments that keep rain out, like raincoats or rain boots.
A raincoat. The most natural way to refer to a waterproof coat.
It looks like rain, so let's take a raincoat.
A traditional or casual raincoat, often made of vinyl or rubber. Slightly old-fashioned or used for children's rainwear.
Rain boots, waterproof footwear.
Go out wearing rain boots.
The action of treating something to make it waterproof.
Completely impervious to water, often used in science or engineering.
Impermeability to water. A technical term used in geology, civil engineering, etc.
This layer is impermeable to water.
In Japanese, 防水 (bōsui) is often used for both 'waterproof' and 'water-resistant'. For 'water-repellent' (surface treatment that makes water bead up), 撥水 (はっすい, hassui) is more precise. If you need to distinguish, use 撥水 for water-repellent and 防水 for waterproof.
When describing an item, you can say 防水の + noun (e.g., 防水のバッグ) or simply use 防水 as a prefix (防水バッグ). Both are natural.
耐水性能をテストする
to test waterproof performance
Put a raincoat on the child.